Antifreeze



United States Patent No Drawing. Application December 26, 1951, SerialNo. 263,487

6 Claims. (Cl. 252-75) The present invention relates to an electrolyteor salt base anti-treeze liquid for cooling systems and, moreparticularly, it relates to a calcium chloride liquid antifreeze for usein the cooling systems of internal combustion engines that does notcorrode or impair the walls of the cooling system.

Calcium chloride has always been recognized as an excellent freezingpoint depressant. However, the high corrosive enect, and particularlythe electrolytic corrosive effect, or calcium chloride solutions uponthe metal walls of cooling systems has precluded its use in thiscapacity. Attempts have been made in the past to add corrosioninhibitors to the calcium chloride solution but such corrosioninhibitors have always proved unsuccessful. This is mainly due to thefact that the modern internal combustion engine has at least four, andsometimes six, dilferent metals therein which are exposed to the actionof the calcium chloride solution. In such cases, although one inhibitorwas successful in protecting a particular metal, it would be found tohave an extremely deleterious effect on another metal. Thus, it becamenecessary to add inhibitors for the inhibitors. The addition of eachadded inhibitor, however, only brought along new problems peculiar tothat-inhibitor to that to date no completely efiicient inhibiting systemhas been devised for calcium chloride anti-freezes to be used ininternal combustion engines. I

Accordingly, anti-freezes other than the salt base type have come intouse. These anti-freezes are of the organic liquid type and as such donot cause electrolytic corrosion. Unfortunately, these organicanti-freezes are relatively expensive and in times of raw materialshortages have placed a heavy drain on critical raw materials. At thesame time, they do not attain as low a freezing point as do the calciumchloride anti-freezes.

In any attempt to produce an efficient corrosion inhibiting system forelectrolyte base anti-freezes there are several factors to beconsidered. One of these factors is hydrolysis of the electrolyte baseFor example, in the case of calcium chloride, hydrolysis will producefree hydrochloric acid which attacks the metal walls of the coolingsystem.

Another factor to be considered is aeration. Although the coolingsystems of internal combustion engines are closed systems for allpractical purposes, they still admit air from the atmosphere and thuspermit free oxygen to enter the coolant. Oxygen, of course, will tend tooxidize the metal surfaces of the cooling system. With increasedcirculatory motion of the coolant, oxygen unsaturated liquid is broughtto the surface where it is exposed to the atmosphere of the air andtakes on oxygen. Since a high velocity of the coolant in the system isdesirable, it becomes necessary to device an anti-freeze whereinaeration can have no elfect.

A still further consideration is the temperature of the coolant.Although a higher temperature will dispel some of the dissolved oxygen,the increased temperature Will augment the rate of hydrolysis of calciumchloride thus producing more free acid to attack the metal wa ls.

However, the most troublesome factor in the production of a goodelectrolyte base anti-freeze is the constant electrolytic action thattakes place between the electrolyte base solution and the metal walls ofthe cooling system. This phenomenon must be eliminated or at leastreduced to a satisfactory minimum if a successful salt basenon-corrosive anti-freeze is to be produced. In an attempt to overcomethis electrolytic effect, mechanically produced barrier coatings betweenthe solution and the metals as well as chemically produced barrier filmsor passivators, have been employed. Such coatings and films do achievetheir protective purpose when the coolant is in a quiescent state, butonce the coolant has begun to circulate then the protective coatings areeroded away, particularly at places where the circulatory motion of theliquid is violent, so that the surfaces of the metal are exposed to theelectrolytic action of the salt base solution. Due to the highertemperature during the circulatory phase, the electrolytic rate betweenthe salt and the metal walls will increase. This electrolytic increaseis in addition to the increase of both the hydrolysis and erosionelfects taking place during the circulatory stage. Thus, in any suitableelectrolyte antifreeze, it becomes necessary to deal with both thequiesfent phase and the circulatory phase of the cooling i uid.

l have invented an electrolyte base anti-freeze for internal combustionengines which employs a salt, such a It is an object of this inventionto provide a salt base anti-freeze which has an extremely low freezingpoint temperature and which will not attack the walls of cooling systemat both high and low temperatures.

It is a further object of this invention to provide a salt baseanti-freeze solution that is suitable throughout its circulatory andquiescent phases.

Moreover, it is an object of the present invention to provide acolloidal solution or dispersion for use with a salt base anti-freezewhich will overcome the corrosive qualities of a salt base due tohydrolysis, aeration and electrolytic action.

An advantage of the present invention is that due to its high boilingpoint and low freezing point it can be employed as a permanent typecoolant suitable to both summer and winter weather.

A further advantage resides in the fact that my salt base anti-freezehas a higher specific heat than the present types so that its capacityto take up heat is superior to that of the present alcohol and glycoltype anti-freezes.

In addition, since my salt base anti-freeze has a higher specificgravity than the present type anti-freezes, a greater volume of coolantwill be circulated by the Water pumps at any given speed thus enhancingthe cooling effect.

A still further advantage flowing from my invention is that it displacesthe use of the more expensive organic chemicals as anti-freezes.

Moreover, it has the advantage that the beneficial freezing depressanteffect of a salt base solution can be aitftained without theaccompanying deleterious corrosive e ects.

Other objects and advantages of the present invention will become moreapparent as it is described in detail below.

In accordance with the present invention, I have provided a salt baseanti-freeze comprising a calcium chloride-sugar solution, a colloidalsolution or dispersion of water and starch, and other corrosioninhibiting and lubricating agents.

The basic formula for compounding my novel antifreeze is shown below:

TABLE A Ingredients: Percentage by weight Calcium chloride 22-36 Water72-58 Sugar A 4 Sodium nitrate 0.2 Triethanolamine 0.6 Soluble starch0.3 Butyl Cellosolve 0.5 n-Butylalcohol 0.2 Barium hydroxide 0.05Dibutyl phthalate 0.05 Urea 0.05 Octyl alcohol 0.05

It is to be expressly understood that my anti-freeze does not have to bemade with strict adherence to the above percentages, but that thesepercentages may be reasonably departed from without effecting theinvention. However, it is pointed out that the total percentage of waterand calcium chloride present in the anti-freeze should approximate 94%.

In compounding my non-corrosive anti-freeze, hard or soft water may beused. If hard water is employed, several of the ingredients added to thewater are capable of softening the water. The main water softeningcompound added to the water is barium hydroxide, which will removemagnesium sulphate, calcium sulphate, sulphuric acid, carbonic acid andcarbon dioxide. Moreover, without such a compound as barium hydroxide orone similar to it to keep the solution on the alkaline side, thehydrochloric acid formed by hydrolysis of the calcium chloride solutionwould attack the walls of the cooling system. This, of course, is inaddition to the attack on the walls due to the electrolytic action ofthe calcium chloride.

The calcium chloride employed may either be in the anhydrous or hydratedform. However, in the above formula, the percentages are based on theuse of anhydrous calcium chloride. Sugar is employed in the antifreezeto prevent the calcium chloride from crystallizing out of solution dueto vaporization when the anti-freeze is at a high temperature such aswhen the engine has been running for a long period of time.

The aqueous solution of calcium chloride and sugar form what may bethought of as the basic solution since they constitute the majorportions of the anti-freeze.

Without limiting myself thereto in any manner, shape or form, I wouldlike to suggest at this point the probable theories that explain theaction of the following added ingredients which permit my salt baseanti-freeze to be non-corrosive. However, it is to be expresslyunderstood that I am not suggesting that this theory is the onlyexplanation of the action of the added ingredients.

Sodium nitrate has long been known to have the function of a passivator.In such capacity the sodium nitrate will protect the aluminum walls ofthe cooling system by reacting therewith to form a film of aluminumoxide. This film of aluminum oxide is one of the barriers or filmsdevised to prevent corrosion of the metals of the cooling system.

In addition to this aluminum oxide film, urea is added to the solutionto produce a protective coating on the walls of the cooling system. Theurea forms a complex compound, the constituency of which is unknown, butwhich serves as an excellent protective for the walls of the system,particularly during the quiescent stage.

Although the solution now has ingredients which form protectivecoatings, namely aluminum oxide film and the coating of urea complex,these are still insufficient to protect the cooling system adequately.This is because in the circulatory phases, the coolant will wash anderode away, at least partly, these two above barriers thereby exposingbare metal surfaces of the cooling system to the electrolytic action ofthe calcium chloride solution. This electrolytic factor is the mostdifficult one to control in the achievement of the non-corrosive saltbase anti-freeze.

Accordingly, my anti-freeze includes a colloidal solution or dispersionwhich is designed to overcome this effect. This colloidal dispersioncomprises Water, soluble starch and triethanolamine. The soluble starchis to be considered as the dispersoid and the water as the dispersingmedium. In choosing a disperoid for my invention, a compound must besought which has the following properties. First, the dispersoid must bean organic compound since an inorganic dispersoid presents too great anelectrolytic effect to be employed with calcium chloride. Second, thedispersoid must be stable so that it does not lose its colloidalproperties and permanently coagulate. Third, the dispersoid must bechemically inert so as not to react with the other ingredients of theanti-freeze solution. Fourth, the dispersoid must be reversible, i. e.,if the dispersoid particles should temporarily coagulate, they mustpossess the ability to return m colloidal state.

I have foundthat boththe saccharo and proteinwate-r colloids have theabove-four required properties.

However, of these groups I prefer the use of soluble starch. The solublestarch molecules due to their large surface area, exhibit a strongtendency to absorb ions in. solution and thus become electricallycharged themselves. However, if the particles are deprived of theirelectrical charge they will surrender the colloidal state and coagulate.This occurs when there is an electrolytic action between the exposedwalls of the cooling system and the electrolytic salt base. When thiselectrolytic action commences, the dispersoid particles will coagulateand form an augmentative protective coating on the bare metal Walls Oncea barrier has been set up between the calcium chloride and the metalwalls, electrolytic action stops. However, there are still left thecoagulated starch particles. If the dispersoid is irreversible, all ofthe colloid will in short time coagulate and be subjected to erosiveaction during the circulatory phase. Thus the anti-freeze is eventuallyrendered use less. However, by choosing a reversible dispersoid, thestarch particles will return to the colloidal statethus creating a freshsupply of colloid to prevent electrolytic action between the calciumchloride and the bare metal wa ls.

In addition, the dispersoid should have a specific gravity which is thesame as or greater than the specific gravity of the entire solution, ifit is to serve as an effective coating agent. If its specific gravitywere less than as a whole, the coagulated particles would tend to riseto the top of the solution and thus not form a uniform coating over thebare metal surfaces of the cooling system.

Triethanolamine serves a double function in my antifreeze. Not only doesit act in its well knowncapacity as a stabilizer for the water andsoluble starch, but it also is a neutralizer for acid formed by thedisassociation of calcium chloride. It thus augments the alkaline effectof the barium hydroxide.

I have also found that triethanolamine itself is insufficient as astabilizer since large quantities are required to form a suitablestarch-water colloid. It is well known that triethanolamine may be usedin quantities of 5% and more to form stable colloids. However, when suchlarge quantities are employed in my anti-freeze, the entire solutionwill become too viscous and therefore unsatisfactory. Thus, it becomesnecessary to seek the aid of an agent which enhances the stabilizingeffect of triethanolamine. Such an agent is butyl Cellosolve (ethyleneglycol monobutyl ether). The combined efiect of the triethanolamine andbutyl Cellosolve provide for a very stable colloid.

Dibutyl phthalate is primarily added as a lubricant during thecirculatory stage of the coolant. As a lubricant it oils the surfaceWalls of the cooling system by providing a fine coating upon the walls.Furthermore, the dibutyl phthalate acts as an agglutinant for any of thecoagulated starch coating that remains on the surface walls of thesystem. Although most of the starch will go back into colloidal state,there is a certain minor portion which will remain coagulated. It isthis minor amount that the lubricant will agglutinate, thus forming afirmer starch coating. One reason that l have chosen dibutyl phthalateis because its specific gravity that of the solution is slightly higherthan that of water thus insuring its complete dispersion in theanti-freeze solution during the circulatory stage.

I have, moreover, found that if n-butylalcohol is added to theanti-freeze, it serves as an excellent solvent for the organic materialsemployed in the anti-freeze. However, the addition of such compound isnot necessary to the success of my invention.

Octyl alcohol is incorporated into the anti-freeze because of itsanti-foaming qualities and of its evaporation depressant effect, i. e.,it prevents loss of water. Although I prefer to use secondary normaloctyl alcohol (2-oc-' tanol), other octyl alcohols, such as primarynormal octyl alcohol (l-octanol) will also suffice for my purposes.

Thus, in operation, anti-freeze works as follows in order to preventcorrosion of the cooling system. The sodium nitrate and the urea eachrespectively form a film of aluminum oxide and a coating of urea complexade'-' quate to protect thecooling system during the quiescent stage,However, when the engine is running andpthe coolant is circulating, as eawarl y cooling system.

At this point, electrolytic action will these protective barriers-"willbe exposing; the metalwalls of the initiate between the calcium chloridesolution and the metal walls. Once this electrolytic action commences,the electrically charged starch particles in the colloidal state willlose their charges and coagulate out on the exposed metal walls forminga suitable coating and barrier between the calcium chloride and thecooling system. It is true that in time the starch coating for the mostpart will return to colloidal state, but in that time a new film ofaluminum oxide and a new film of urea complex will have formed to coverthe eroded area. Thus, in the circulatory phase, there is alwaysprovided some means of protecting the metal walls against theelectrolytic action and other corrosive effects of the calciumchloride-water coolant. Moreover, the dibutyl Example 4 Weight P tIngredients by Green 5 Grams Weight Water 3, 785 5a. calcium chloride(dihydrate). 2, 854 39. 9 sucrose 350 4. 0 10 barium hydroxide 3 04potassium nitrate. 12 2 morpholine 40 6 soluble starch 30 4 butylCellosolve.-- 4O 6 n-b utylaleohol 17 2 dibutyl phthalate. 2 .03 15octyl alcoh 2 .03 urea 2 03 phthalate lubricant will add to theprotective coating.

Below is an example of a typical formula for my novel anti-freeze. I

Example 1 Weight P t Ingredients by Grams Weight Water 4, 340 67. 9calcium chloride 1, 710 26. 7 sucrose 260 4. 1 barium hydroxide- 2 03sodium nitrate 6 09 triethanolamine. 25 4 10 .2 20 3 l0 2 dibutylphthalate. 2 03 octyl alcohol (sec-normal) 2 03 urea 2 03 Althoughpreferably I employ sucrose, other water soluble carbohydrates, suchas'the mono-, .di-, and trisaccharides may be equally employed in placethereof.

Potassium nitrate and lithium nitrate may be employed as passivators inplace of sodium nitrate.

Furthermore, hydroxy alkylamines, such as diethanolamine andmonoethanolamine, and also morpholine may be employed in place oftriethanolamine. Moreover, Carbitol (monoethyl ether of diethyleneglycol) and butyl Carbitol (monobutyl ether of diethylene glycol) may besubstituted in the basic formula for butyl Cellosolve.

Likewise, diethyl phthalate and isoamyl phthalate have also been foundsatisfactory as lubricants in place of dibutyl phthalate. Below are someexamples which employ the various different equivalent compoundsdescribed above:

Example 2 Weight P t In edients by P gr Grams Weight Water 4, 394 65. 7calcium chloride 1, 881 28. 2 sucrose 300 4. barium hydroxide 2. 33 04potassium nitrate 8 1 dinthmmlnmlne 3O .4 soluble starch 20 3 Carbitol25 4 n-buty 12 2 ethyl nhthalata 2 03 octyl alcohol 2 03 urea 2 03Furthermore, the calcium chloride may be added in hydrate form as shownin Examples 3 and 4 below.

Example 3 Weight Percent In edients by Grams Weight Water 3, 785 54. 5calcium chloride (dihydrate) 2, 718 39. 0 sucrose. 325 4. 7 bariumhydroxide 2. 67 .04 sodium nitrate .1 monoethanolam 35 5 soluble starch25 4 butyl Car-bitch.-- 30 .4 n-butylalcohol 15 2 amyl phthalate 2 .03octyl alcohol 2 03 urea..-. 2 .03

In Table A, of course, the percentage ranges for the calcium chlorideand water have already been given. It should be noted that in Examples 3and 4, the percentage of calcium chloride is based on the dihydrate. Insolution, the water of the dihydrate will add to the water used todissolve the calcium chloride thereby bringing tlliese examples intoconformity with Table A and the c aims.

Examples 1 through 4 show the sugar ranging from 4.1% to 4.9% by weightor approximately 4 to 5%.

Table A and the above examples show the barium hydroxide ranging from.03% to .05 by weight.

The above examples and Table A also disclose that the nitrate compoundsrange from 0.1 to 0.2% by weight; the organic nitrogen compounds rangefrom 0.4 to 0.6% by weight; the soluble starch ranges from 0.2 to 0.4%by weight; and the ethylene glycol ethers range from 0.3 to 0.6% byweight.

It is to be expressly understood that the above examples are onlyrepresentative of my invention and I am not in any way limiting myselfthereto, particularly since any combination of the equivalentingredients will result in a suitable and satisfactory anti-freeze.

However, regardless of the particular anti-freeze employed within thescope of my invention, the pH should range between a pH of 7 and 9.

In carrying out the manufacture of my anti-freeze, a tank is filled withwater at room temperature. About 5% of the total amount of wateremployed is kept apart from p reparation of the soluble starch solution.To the remaming amount of water the calcium chloride is gradually addedand evenly dissolved. Next, the sugar is added to the calcium chloridesolution until it is comthese three ingredients comprise what may beconsidered the basic solution, barium soluble undesirable constituentsthat should be removed from the solution as soon as possible. The entiresolutron lS stirred for approximately five minutes to insure completesolution and then filtered to remove undesirable msoluble impuritiespresent in the calcium chloride, sugar and barium hydroxide.

Due to the heat of solution, the solution will now have a temperature ofapproximately 140 F. It is necessary that the solution be permitted tocool to approximately F. before the other ingredients are added. Whenthe solutionjs at the proper temperature, sodium nitrate, urea,triethanolamine and butyl Cellosolve are added in that respective order.

Meanwhile, the soluble starch solution should be prepared in thefollowing manner. The starch is added to about /3 of the water which hasnot yet been placed in the solution. This water should be at roomtemperature. The starch is stirred until the mixture has an homogeneousconsistency. The remaining of the homogeneous mixture of soluble starchand cool water so as to provide a thorough and even dissolution of thesoluble starch in the major solution. This total soluble starchpreparation is then mixed into the major solution containing calciumchloride and sugar.

The n-butylalcohol, the dibutyl phthalate and octyl alcohol arerespectively added to the entire solution, which is then agitated toattain a uniform distribution of ingredients and finally permitted tocool down to approximately 86 F. before it is placed in suitablecoutainers.

Having thus described my invention, I claim:

1 .,A non-corrosive anti-freeze solution for internal combustion enginescomprising from 22 to 36% by weight of calcium chloride, from 58 to 72%by weight of water, said calcium chloride and said water approximating94% by weight of the solution, approximately from 43o 5% of a sugar ofthe class consisting of mono-, di-, and tri-saccharide and sucrose,approximately from 0.1 to 0.2% by weight of a nitrate of the classconsisting of sodium, potassium and lithium nitrate, approximately 005%by weight of barium hydroxide, approximately from 0.4 to 0.6% by weightof a nitrogen compound of the class consisting of mono-, di-, andtriethanolamine and morpholine, from 0.2 to 0.4% by weight of solublestarch, s'aid starch and said water forming a reversible colloid in thesolution, and approximately 0.05% by y7veigh1t (91f urea, said solutionhaving a pH range between an.,. l I I 2. A non corrosiye anti-freezesolution for internal combustion engines con'lpri sirig from 22. to 36%by weightlof calciumchloride, from 5 8 to 72% by weight qij water, said{calcium chloride and said water approxim t n 94% by, wei to es i iomapp o e y from4 to 5%. by, Weight of sucrose, approximately from 0.1 to0.2% by weight of sodium nitrate, approximately 0.05% by weight ofbarium hydroxide, approximately from 0.4 to 0.6% by weight of a nitrogencompound of the class consis'tingof mono-, di-, and tri-etha'nolamineand morpholine, from 0.2 to 0.14% by weight of soluble starch, saidstarch and said water forming a reversible colloid in the solution,

and approximately 0.05% by weight of urea, said solution having a pHrange between 7a11 .9-.

3. A r on-corrosive anti-freezesolution for internal combustion enginesin accord with claim 1 wherein said soluble starch has a specificgravity not less than the p i r V YPHa u iQ V t. .7 4. A non-corrosiveanti-freeze solution; in accord with claim l wherein said solutionfurthercornprises approximately from 0.4 to 0.6% by weight of a'compound of the class consisting of monoethyl monobutyl ether ofdi'e'thylene glycol, and ethylene glycol monobutyl ether, andapproximately 0.05%

by weight of combustion engines comprising from 22 to weight of calciumchloride, ,from 58 to 72% t of water, said calcium 36% by by weightchloride and said water approximating 94% by weight of the solution,approximately from 0.1 to 0.2% by weight of a nitrate ofrthe classconsisting of s'odium,,potassium and lithium nitrate, approximately0.05% mately from by weight of barium hydroxide, approxl- 0.4 to 0.6%

by weight of a nitrogen com pound of the class consisting of mono-, di,and triethanolamine and weight of soluble starch, said starch ing areversible colloid in the solution, 0.005% by weight of urea,

morpholine, from 0.2 to 0.4% by and said water formand approximatelysaid solution having a pH range between 7 and 9.

6..A non-corrosive anti-freeze solution for internal combustion enginesweight of calcium chloride, from 58 to 72% comprising from 22 to 36% byby weight of water, said calcium chloride and said water approxmating94% byweight of the solution,

approximately from 0.1 to 0.2% by w eight of sodium nitrate,approximately 0.05% by weight of barium hydroxide, approximately 0.4 to0.6% by weight of tri-ethanolamine, from 0.2 to 0.4% by weight ofsoluble starch, said starch and said water forming a reversible colloidin the solution,

and approximately having a pH range 0.05% by weight of urea, saidsolution between 7 and 9.

References Cited in the file of this patent when STATES PATENTS etheroidiethylene glycol,

1. A NON-CORROSIVE ANTI-FREEZE SOLUTION FOR INTERNAL COMBUSTION ENGINESCOMPRISING FROM 22 TO 36% BY WEIGHT OF CALCIUM CHLORIDE, FROM 58 TO 72%BY WEIGHT OF WATER OF CALCUIM CHLORIDE AND SAID WATER APPROXIMATING 94%BY WEIGHT OF THE SOLUTION, APPROXIMATELY FROM 4 TO 5% OF A SUGAR OF THECLASS CONSISTING OF MONO-, DIAND TRI-SACCHARIDE AND SUCROSE,APPROXIMATELY FROM 0.1 TO 0.2% BY WEIGHT OF A NITRATE OF THE CLASSCONSISTING OF SODIUM, POTASSIUM AND LITHIUM NITRATE, APPROXIMATELY 0.05%BY WEIGHT OF BARIUM HYDROXIDE, APPROXIMATELY FROM 0.4 TO 0.6% BY WEIGHTOF A NITROGEN, COMPOUND OF THE CLASS CONSISTING OF MONO-, DI-, ANDTRI-ETHANOLAMINE AND MORPHOLINE, FROM 0.2 TO 0.4% BY WEIGHT OF SOLUBLESTARCH, SAID STARCH AND SAID WATER FORMING A REVERSIBLE COLLOID IN THESOLUTION, AND APPROXIMATELY 0.05% BY WEIGHT OF UREA, SAID SOLUTIONHAVING A PH RANGE BETWEEN 7 AND 9.